The field of the present invention relates generally to microsound (sound-wave analog of microwave) components and circuitry. More specifically, the present invention relates to a single crystal fiber acoustic waveguide, and its use in a single crystal fiber acoustic waveguide system.
Microwave techniques used in the manipulation of electromagnetic energy are now available, as a result of the development of microsound apparatus, for the manipulation of acoustic energy. Extensive research has been performed on guided acoustic wave devices utilizing acoustically slow epitaxial crystalline layers grown over faster wave single crystals.
A strip of slow wave single crystal material grown on a faster single crystal substrate allows the acoustic energy to be guided by or follow the strip, in a manner analogous to microwave energy following a dielectric microwave guide. Microsound guides are available with slow wave strips designed to guide acoustic energy around gradual bends. Coupling technique are available for interconnecting such guides, to transfer acoustic energy between them.
Through means of coupling such waveguides together and through appropriate design of the slow epitaxial grown layer, many devices including hybrides, filters, directional couplers, isolators, switches, grators, phase shifters and amplifiers can be provided. Such circuits are generally five orders of magnitude smaller in volume than analogous microwave circuits.
Presently, the maximum acoustic delay available from bulk crystals cut to substrate size is about 10 microseconds. Spiraling the slow waveguide has been used for relatively long delays; however, in such cases, as the simulation of radar range time, much longer delays are required. Recent advances in the art of growing crystal fibers now makes long length crystal acoustic delay lines feasible.